In the field of laboratory animal management, in particular with small animals such as mice or guinea pigs, cages are used, in particular sealed cages suitable to be connected to a ventilation system. The cages are usually housed side by side and stacked on shelves constructed for this purpose, each in a specific seat provided with guides suitable to receive and support the cage; the shelf can be accessible from two opposite sides, allowing two sets of cages to be housed. Each shelf can house several tens of cages, for example eighty cages, and is provided with circulation systems to connect the cages to a ventilation unit. Usually the cages are connected automatically to said systems as soon as the cage is inserted in the seat. The operator can connect the circulation systems of the various shelves which are mutually served by a single unit.
A large number of shelves can be present in laboratories and to optimize the space they can be placed side by side, in contact or almost with one another so that, to access the cages it is necessary to move the shelves to create a passage between two adjacent shelves, i.e. placed with the long sides, those accessible, against one another. Displacement takes place transversely to the long side of the shelf, and the shelves can be moved in sequence, to free from time to time the space between two pairs of subsequent shelves and access all the cages for the operations, similarly to the case of archives with moving shelves. The shelves are generally provided with their own wheels, for example wheels free to swivel in the direction in which the shelf is pushed, so that they can be moved in all directions, and not in transverse direction, so that they can also be moved out of the formation. Given the considerably weight that a shelf can have when loaded with cages, movement is difficult and tiring. Moreover, the wheels can damage the floor on which they rest and move.
The problem is further increased by the fact that more than one shelf, for example two, can be mutually aligned, mechanically joined and connected to the same ventilation unit, so that it is necessary to move them together, and together with the unit serving them, an operation that is considerably difficult and made even more difficult by the elasticity of the structure of the shelf.